One aspect of the ability of a person to see an object is sensitivity to glare. Ophthalmologists and optometrists determine sensitivity to glare by shining a small light in the patient's eye and making a skilled judgment as to whether the patient is more or less sensitive to glare.
U.S. Pat. No. 3,684,355 discloses a glare tester which uses a series of targets on a film strip. A source of light illuminates the target and the same source of light passes through filters to provide a variable glare to the eye. The patent also shows another form of glare tester in which light is passed through filters and varies the illumination of a target. A separate circular light surrounding a port provides a source of glare. A separate glare shield ring prevents light from the annular ring illuminating the target. These devices rely upon varying the illumination of the target image or the amount of glare. The filter strips and the target strips must be coordinated and the device is complex because of all the moving parts and the necessary coordination of the different separate film strips and target.
The inventors have provided a simpler tester by using a plurality of unique slides in a standard Fairchild Syncro-Slide 35 Projector Model No. 3501 which is simple to operate and inexpensive. The cost is reduced because of the adaptability of the concept to the use of a standard slide projector. The concept could be used with any other standard slide projector having its own screen.
We provide a glare susceptibility testing device comprising: A planar member having target image on its surface, a contrasting surface surrounding the target image and which provides a contrast with the target when light is directed to the target and the contrasting surface and a translucent surface surrounding the contrasting surface; and means supporting the planar member and directing light to one side of the planar member.
Other details, objects and advantages of this invention will become apparent as the following description of the present preferred embodiment proceeds.